Tulsa is the second-largest city in the state of Oklahoma and 45th-largest in the United States. With an estimated population of 384,037 in 2007, it is the principal municipality of the Tulsa Metropolitan Statistical Area, a region of 905,755 residents projected to reach one million between 2010 and 2012.
In 2007, the Tulsa-Bartlesville Combined Statistical Area had a population of 955,643 residents. The city serves as the county seat of Tulsa County, the most densely populated county in Oklahoma, and extends into Osage, Rogers, and Wagoner counties.
For most of the 20th century, Tulsa held the nickname "Oil Capital of the World" and played a major role as one of the most important hubs for the American oil industry. Tulsa has been credited as the birthplace of U.S. Route 66 and the home of Western Swing music.
Tulsa was once heavily dependent on the oil industry, economic downturn and subsequent diversification efforts created an economic base in the energy, finance, aviation, telecommunications and technology sectors. The Tulsa Port of Catoosa, at the head of the McClellan-Kerr Arkansas River Navigation System, is the most inland riverport in the U.S. with access to international waterways.
Located in Tornado Alley, Tulsa frequently experiences severe weather. It is situated on the Arkansas River at the foothills of the Ozark Mountains in northeast Oklahoma, a region of the state known as "Green Country."
Considered the cultural and arts center of Oklahoma, Tulsa houses two world-renowned art museums, full-time professional opera and ballet companies, and one of the nation's largest concentrations of art deco architecture. In 2005, the city was selected as one of "America's Most Livable Large Cities." People from Tulsa are described as "Tulsans."